Reps. Frank Thompson (D-N.J.) and John MURPHY (D-N.Y.), lame-duck congressmen who in their time were House kingpins, were convicted last night of charges stemming from the FBI's Abscam sweep against political corruption.

After 22 hours of deliberation over two days, a U.S. District Court jury in New York found the two veteran legislators guilty of varying counts of conspiracy and, in Thompson's case, a charge of bribery.

Murphy, chairman of the House Merchant Marine and Fishers Committee, was found guilty on three counts -- conspiracy, conflict of interest and accepting an illegal gratuity. He was found innocent of a bribery charge.

Thompson, chairman of the House Administration Committee, was found guilty of accepting $50,000 from undercover agents, conspiracy and accepting an illegal gratuity. He was found innocent of conflict of interest.

Thompson could face up to 22 years in prison, while Murphy could face nine years as a result of last night's verdict, handed down by the jury of eight men and four women at 9:20 p.m.

Although both men were defeated last month in their reelection campaigns, their convictions represented the biggest quarry in the FBI's celebrated undercover operation, in which agents passed themselves off as representatives of fictitious Arab sheiks who supposedly wanted held with immigration problems.

Federal juries earlier convicted Reps. Michael Myers (D-Pa.) and John Jenrette (D-S.C.) on charges stemming from the Abscam probe. They, too, were defeated in reelection bids. The trial of Rep. Richard Kelly (R-Fla.), another loser last month, is scheduled to start today in Washington, while Rep. Raymond Lederer (D-Pa.), reelected last month, is to go to trial in January. Awaiting a trial date on Abscam-related charges is Sen. Harrison A. Williams Jr. (D-N.J.), chairman of the Senate Labor and Human Resources Committee.

As in the Myers and Jenrette trials, the government used extensive video and audio recordings of different meetings between Murphy and Thompson and the FBI's undercover operatives.

But the tapes failed to show clearly that Murphy knew there was $50,000 in a briefcase that the agents handed to him during one of their meetings. Videotapes did not show the nine-term Staten Island congressman picking up the briefcase.

Shortly before the verdict was reached last night, U.S. District Court Judge George Pratt told jurors, in response to a question, that "actual possession of the briefcase itself by Murphy would not have to be shown" to determine that he received part of the money.

Videotapes shown at the trial portrayed a confederate, Philadelphia lawyer Howard Criden, accepting the money with the understanding that it eventually would to to the legislators.

Both defendants insisted on their innocence during the trial and Thompson, 62, a House member since 1954, denied the government's charges during his two days of testimony. Murphy, 54, did not testify and offered no witnesses in his behalf.

In their defense, the two men claimed they did not know the FBI's briefcases contained money, while arguing that they had attended the clandestine meetings in order to discuss possible investments in their districts by the "sheiks."

As jury foreman Jerome Karpf, a journalism professor, announced the verdicts in the crowded Brooklyn courtroom, neither defendant showed emotion. Thompson took notes; Murphy sat impassively.

Afterward, both men said they intended to appeal the convictions. Murphy, with his pregnant wife at his side, would say only, "We will appeal this decision." Thompson, accompanied by his wife, Evelina, said "I'll be as responsive and polite as I can -- and I want to get out of here. . . . Obviously, I'm upset and disappointed. I maintain my innocence."

The Brooklyn jury's decision came just a week after another federal judge in Philadelphia overturned Abscam convictions of two city councilmen, in part on grounds that the FBI had entrapped them.

Judge Pratt said the jury had voted unanimously not to discuss its work with news reporters. However, an apparently key element in the prosecution's case was the testimony of Rep. John Murtha (D-Pa.), a star witness who testified that Thompson told him that Thompson, Murtha and Murphy would share in a $50,000 bribe.

Defense lawyers contended that Criden, who was convicted of bribery and conspiracy in the Myers trial, misled Thompson and Murphy about the purpose of the meetings with the FBI agents and kept the money for himself.

Prosecutor Thomas Puccio, however, argued that Murphy and Thompson were too sophisticated not to know the briefcases contained payoff money. Thompson, while insisting on his innocence, admitted during testimony that he had made "inaccurate" statements to FBI agents who interviewed him on Feb. 2, a day before the Abscam investigation became public.